The environment in which the invention is described is a windshield washer liquid reservoir tank for a vehicle and the invention may be used on any tank for any purpose. The devices of the prior art are complicated in design, construction, and operation; expensive to manufacture, assemble, repair, and replace; not desirably satisfactory in use; and inaccurate or unstable in signaling due to opening and closing the electrical contacts repeatedly when the liquid level is near a pre-selected point such as when refilling is indicated as desirable. The repetitious on-off condition causes the signal lamp to flicker thereby annoying and distracting the operator. In most prior art devices this flickering is occasioned by bouncing of the float resulting from vibration, the gravational effect on hills, and the centrifugal effect of turning and sudden starts and stops; all of which causes the liquid to rise and/or fall relative to the tank level which in turn causes the float to actuate the switch when the liquid level is not down to the refill point resulting in a false signal. The float thus is not protected against sudden changes in the actual liquid level at the float. Also the float does not have desirable buoyancy to render it effective with reliability such as in one case where the center of the float is removed for a guide pin. Another failure of the prior art devices is that they will jam in the "on" or "off" position giving a false indication of full or of needing a refill. It is recognized that the operator should be advised not to let the tank go dry not only to provide adequate liquid supply, but also to prevent the pump losing its prime and/or running dry and being damaged.